Some electronic systems include power supplies for receiving an input voltage and converting this input voltage to a desired output voltage to be supplied to components in the electronic system that performs the desired function of the system.
For example, a computer system includes a power supply that receives an input voltage and converts this input voltage to an output voltage that is applied to, for example, a motherboard, disk drives, a monitor as well as other components. Ideally, the power supply operates as efficiently as possible, where efficiency relates to the portion of input power received by the power supply that is converted into output power provided by the power supply.
A variety of different types of power supplies exist, with a particular type utilized in a given application being determined by a variety of factors such as the amount of power needed and the efficiency of the power supply. Different types of power supplies have different topologies. One type of power supply is a DC-to-DC voltage converter that converts a supplied voltage at a first level to a DC output voltage at a desired second level. There are many different converter topologies that may be utilized for DC-to-DC converters. The type of DC-DC converter is selected based on a given application which is determined at least in part on the amount of output power needed. For example, “flyback” topology may be used when an amount of output power needed is less than 100 watts. A “push-pull” topology may be used when an amount of output power is between 100 watts to 500 watts and a “full bridge” topology may be used when an amount of output power is beyond 500 watts.
The particular topology of a voltage converter will have an efficiency that varies as a function of the power level being supplied to the output. For example, a converter of a given topology providing an output that is significantly less than it is capable of may have an efficiency that is low. Take the case of a full-bridge voltage converter which, as previously mentioned, is typically utilized where the output power to be provided is greater than 500 watts. If only 100 watts is needed at the output, the full-bridge converter can supply this required output level but the efficiency of the converter in doing so may be unacceptably low.
A voltage converter is typically formed in an integrated circuit which a customer integrates into their overall electronic system. At present, such a customer must select the integrated circuit for the voltage converter topology that provides the required maximum output power. Under light load conditions, the selected converter must be operated less efficiently.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a voltage converter topology which operates efficiently under both normal and light load conditions.